1. Field of the Invention
The present invention relates to a strain belonging to genus Phellinus, a polysaccharide substance produced from the strain, and use of the polysaccharide substance. More particularly, the present invention relates to a novel Phellinus spp. strain, a novel polysaccharide substance produced therefrom, which shows potent immuno-stimulating activity, and use of the polysaccharide substance in the prophylaxis and treatment of immunity-related diseases, such as cancers and AIDS, and in their mechanism study.
2. Description of the Prior Art
Mushrooms, a kind of higher fungi, are heterotrophic; they take in organic nutrients from the outside through microscopically structured hyphae. In the biosphere, they play a role as a decomposer which degrade complex organic materials into simple inorganic forms and finally return them into nature. Of fungi, most typical mushrooms belong to Basidiomycetes which characteristically form basidia which each bears on its surface four exogenous basidiospores upon coming to maturity. The mushrooms are further classified into Hymenomycetes which actively release spores from exposed hymenia. Representative of Hymenomycetes are Aphyllophorales and Agaricales. Ramaria botrytis, Hymenochaete yasudai Imaz., Climancodon septentrionalis, Coriolus versicolor, and Canoderma applanatum fall under the category of Aphyllophorales and Pleurotus ostreatus, Lentinus edodes, Schizophyllum commune, Tricholoma mastsutake, Amanits muscaria, and Coprinus comatus are placed within the category of Agaricales. 
From times past, it has been known in Oriental herb medicine that many mushrooms belonging to Aphyllophorales, a kind of Basidomycetes, are therapeutically active against various diseases, especially, tumors. In Korea, they have been transmitted from generation to generation as herb medicines or folk medicines and, among the mushrooms, particularly, Phellinus linteus, belonging to the family Polyporaceae, has been regarded as an extremely precious medicine. Phellinus linteus, however, is a very rare species in nature, so that its fruiting body is very difficult to obtain. Further, isolation and artificial culture of the mycelium of Phellinus linteus are regarded almost impossible. Accordingly, advantage has not been actively taken of Phellinus linteus despite its being recognized as a therapeutically very effective agent against tumors.
For treating cancers, various methods including chemotherapy, radiotherapy and surgery are conventionally used. Effective as these therapies are for solid cancer, they are insufficient for the perfect conquest of caners. Particularly, they are helpless for metastatic tumors.
Usually, chemotherapy using anticancer agents, such as adriamycin, and radiotherapy cause serious side-effects. In order to attenuate the side-effects, such an anticancer agent would be administrated at a reduced dose. In this case, however, the therapeutic effect of the chemical becomes poor. What is worse, cancer metastasis cannot be prevented even after taking chemotherapy in treating cancers. Thus, conventional chemotherapy is effective against the growth of cancers to an extent, but cannot completely cure cancers.
An alternative method is to utilize immunosuppressives, known as immunotherapy. Representative examples of the immunosuppressives are cytokines, such as interleukine-2, tumor necrosis factors, etc. Interleukine 2 shows superior therapeutic effects, particularly for cancer metastasis. When being applied for the human body, interleukine-2 is required to be used at such a large amount as to cause serious side-effects. Recent research on novel immuno-stimulating substances which are non-cytokines and show excellent activity against cancer without side-effect, has resulted in the development of Lentinan and OK-432.
For last few years, a new technology in which chemotherapy is used in combination with immunotherapy, known as immunochemotherapy, has been gathering strength. For instance, adriamycin and the immnuonoenhancements are co-administrated to the patients suffering from cancer, with the aim of enhancing the anticancer effects while reducing the side effects of the chemical.
No study on the microbiological and genetical characteristics of Phellinus spp. strains has been, to our knowledge, reported, thus far. Microorganisms, even if the same species, may be significantly different from each other in the kinds and amounts of the materials they produce as well as may show a large diversity in culture conditions, strain stability, and frequency of genetic variation. The first thing to do in researching the fungi, Phellinus, on their valuable products is to select the strains which can produce a large amount of the products and be cultured in broth in addition to being of low genetic variation. Phellinus linteus strains are very diverse and modified in morphology as observed with a microscope, so that they are difficult to identify. However, their classification has been practically dependent on the morphological discrimination under a microscope.
In recent, new DNA analysis methods have been developed for research in population genetics and phylogenetics. Over phenotype analysis methods, the DNA analysis methods have an advantage of being able to analyze genotypes on the basis of evolution rate and heredity tendency. Of them, a restriction fragment length polymorphism (hereinafter referred to as “RFLP”) technique allows the mutation of base sequence to be inferred so as to analyze genotypes (Dowling et al. 1990, 1990. Nucleic acid II: Restriction site analysis. In: Molecular systematics ed by D. M. Hills and C. Moritz. P250-317. Sinauer Associates Press). Because nuclear DNA is too large to easily analyze, organella genomes are usually utilized for DNA analysis (White and Densmore, 1992 Mitochondrial DNA isolation. In: Molecular genetic analysis of populations: A practical approach. Ed by A. R. Hoelzel. P29-58. Oxford university press). Particularly, advantage is taken of mitochondrial DNA. Generally, mitochondrial DNA is smaller in size and faster in evolutionary change rate than nuclear DNA and experiences maternal haploid inheritance, so that mitochondrial DNA is extensively used for study on the genetic structure and history of a population. Particularly, the RFLP of mitochondrial DNA is utilized for the study on inter-species mutation (Foster et al., 1988. Estimation of relatedness between Phythophothora species by analysis of mitochondrial DNA. Mycologia 80:466-478)